1. Field of the Invention
The present invention relates generally to a quantitative analysis for determining amounts of components present in an unknown amount of specimen.
2. Related Background Art
Conventionally, a patient has been required to visit a medical institution and to have his blood, urine, or the like collected and tested, for medical treatments or diagnoses of various diseases. Usually, the test results are not available before the next medical examination or many hours. Hence, there has been a problem that such a test requires a considerably time-and-energy consuming process for both the patient and medical institution.
In order to avoid such a problem, recently, a specimen-collecting card formed, for example, of a filter paper has been proposed. For instance, JP 10-104226 A discloses a blood collecting card. Such a card has been used in the following remote clinical diagnosis system. In this remote clinical diagnosis system, a patient collects blood by himself and the blood collecting card is impregnated with the blood. This is then dried and is then mailed to a medical institution. In the medical institution that has received this, a portion impregnated with the blood is cut out from the blood collecting card and the blood is extracted to be tested with respect to various test items. When the patient visits the medical institution, medical treatments or diagnoses are conducted based on the test results.
When using such a blood collecting card, for example, since the patient himself collects blood as described above, the amount of blood with which the blood collecting card is impregnated is unknown. Hence, it has been difficult to correctly determine the amounts of components in the blood. From this viewpoint, for instance, the following methods have been proposed. In one example of the methods, filter paper capable of retaining a certain amount of blood in a certain area is used. A portion of the filter paper that has been impregnated with blood and has the certain area is cut out and thus the certain amount of blood is secured. In another example of the methods, filter paper having a certain area for retaining a certain amount of blood is used. A saturation amount of blood to be retained is supplied to the filter paper and thus the certain amount of blood is secured.
However, the aforementioned filter papers have the following problems. For instance, when using the former filer paper, the filter paper cut out is required to have been impregnated with blood throughout, and thus selection of the portion to be cut out or a cutting operation is difficult. On the other hand, when the latter filter paper is to be impregnated with a saturation amount of blood to be retained, actually, it is necessary to supply a larger amount of blood than the saturation amount to allow the filter paper to be impregnated sufficiently with the blood. Hence, time and energy are required and thus a great burden is imposed on the patient. Furthermore, when quantitativity is intended to be improved, the manufacture of such quantitative filter papers themselves becomes very complicated and difficult, and the manufacturing cost of such filter papers increases accordingly.
Besides the methods using porous materials such as the above-mentioned filter papers, for instance, there is a method of retaining and preserving a specimen using a capillary tube with the specimen remaining in a liquid state. In this case, however, there is possibility that the specimen thus retained may be dried, or when the blood is recovered from the capillary tube using, for example, a buffer solution, the amount of the specimen contained in the recovered liquid may become unknown and thus the quantitative accuracy may be deteriorated with respect to the amounts of the components actually contained in the specimen.
The present invention at least in its preferred embodiments is intended to provide a quantitative analysis in which even when an unknown amount of specimen is used, amounts of components in the specimen can be measured with high accuracy.
In order to achieve the above-mentioned object, a quantitative analysis of the present invention is used for measuring a concentration of a component to be analyzed in a specimen. The quantitative analysis includes: measuring an amount of a component to be analyzed in a specimen; measuring an amount of a standard component present originally and homeostatically in the specimen other than the component to be analyzed; determining an amount of the specimen from the amount of the standard component thus measured and a known concentration of the standard component in the specimen; and determining a concentration of the component to be analyzed in the specimen from the amount of the specimen thus determined and the amount of the component to be analyzed thus measured. In the present invention, the standard component denotes a substance that is originally present in the specimen and has a concentration maintained to have homeostasis (to be substantially invariable), for example, in vivo.
As described above, in the quantitative analysis of the present invention, not only the amount of the component to be analyzed in the specimen but also the amount of the standard component are measured. Thus, the concentration of the component to be analyzed in the specimen can be determined with excellent accuracy. Accordingly, the quantitativity is improved with respect to the component to be analyzed in the specimen. The standard component is a substance contained homeostatically in the specimen as described above and thus the content thereof in the specimen is known. Hence, its theoretical value (concentration) can be predetermined. Thus, for example, even in the case of a test sample containing an unknown amount of specimen, the rate of content (for example, the dilution or concentration ratio) of a specimen in the test sample can be determined from the ratio between the known concentration of the standard component and the measured amount of the standard component. Then, the concentration of the component to be analyzed actually contained in the specimen can be determined from the rate of content thus determined and the measured value of the component to be analyzed. Furthermore, according to the quantitative analysis of the present invention, it is possible to measure the amount of the component to be analyzed in the specimen without using, for example, a special porous material like one described above in order to improve the quantitativity. Thus, it also is possible to achieve cost reduction. In addition, for example, when a xenobiotica such as a dye, etc. is added as the standard material to the specimen beforehand, a problem in solubility may be caused or there is a possibility that the xenobiotica may affect the detection of the component to be analyzed. However, according to the present invention, since the aforementioned standard component is a substance originally present in the specimen, the standard component does not affect the analysis and an operation for adding such a xenobiotica is not required. Hence, the quantitative operation is simple and convenient. Consequently, the quantitative analysis of the present invention is particularly useful for various tests in clinical medical treatments, for example.
In the quantitative analysis of the present invention, preferably the specimen is retained in a porous material and is then recovered from the porous material to be analyzed. According to the quantitative analysis of the present invention, even when one of various porous materials is impregnated with an unknown amount of specimen collected by a patient himself and this is then dried and is then mailed to a medical institution as described above, the quantitative analysis of components to be analyzed in the specimen recovered as described above can be carried out easily. Hence, it is possible to save the time and energy of both the patient and medical institution, and thus the quantitative analysis of the present invention is useful for various tests in clinical medical treatments, etc., particularly for the remote clinical diagnosis system. Furthermore, the quantitative analysis of the present invention is useful, for example, for analyzing an unknown amount of specimen as described above but is not limited thereto as long as a specimen is retained in the porous material. Besides, the quantitative analysis of the present invention also is useful in the case, for instance, where a specimen retained in a capillary tube is collected as described above.
In the quantitative analysis of the present invention, preferably, the specimen is retained in the porous material, is dried, and is then recovered.
Furthermore, it also is preferable that the porous material retaining the specimen be dipped in an extractant and the specimen be extracted from the porous material to be recovered. As described later, the amount of the extractant is not limited, but preferably, is 1 to 1000 times the porous material by volume. In addition, preferably, a ratio of the extractant to the porous material per volume is constant.
Preferably, the quantitative analysis of the present invention includes: measuring an amount of a component to be analyzed in a test sample containing an extractant and the specimen recovered from the porous material; measuring an amount of the standard component to be analyzed in the test sample; determining an amount of the specimen from the amount of the standard component thus measured and a known concentration of the standard component in the specimen; and determining a concentration of the component to be analyzed in the specimen from the amount of the specimen thus determined and the amount of the component to be analyzed in the test sample thus measured.
In the quantitative analysis of the present invention, preferably, the concentration of the component to be analyzed contained in the specimen is determined by a formula of:
A=Zxc3x97(Y/X),
where A denotes the concentration of the component to be analyzed, Z a measured concentration value of the component to be analyzed in the test sample, X a measured concentration value of the standard component, and Y a known concentration value of the standard component in the specimen.
In the quantitative analysis of the present invention, the standard component is not limited as long as it is contained homeostatically in the specimen. Examples of the standard component include sodium ion (Na+), chloride ion (Clxe2x88x92), potassium ion (K+), magnesium ion (Mg2+), calcium ion (Ca2+), total protein (hereinafter referred to as xe2x80x9cTPxe2x80x9d), and albumin (hereinafter referred to as xe2x80x9cAlbxe2x80x9d). Among them, Na+, Clxe2x88x92, K+, Mg2+, Ca2+, and TP are preferable, Na+, Clxe2x88x92, Mg2+, Ca2+, and TP are more preferable, and Na+, CLxe2x88x92, and TP are particularly preferable.
In the quantitative analysis of the present invention, preferably, the specimen is an aqueous liquid specimen derived from an organism. Examples of the specimen include blood, urine, saliva, lymph, a cerebrospinal fluid, and an intercellular fluid. Among them, a preferable specimen is blood or the intercellular fluid, and a more preferable specimen is blood. Any one of, for example, whole blood, blood cells, blood plasma, and blood serum can be used as the blood specimen. Preferably, the blood specimen is whole blood, blood plasma, or blood serum and more preferably, is blood plasma or blood serum. When the present invention is applied to the quantitation of such a specimen derived from an organism, for example, various diagnoses in clinical medical treatments can be conducted with high accuracy.
In the quantitative analysis of the present invention, the component to be analyzed is not limited. When the specimen is blood (blood plasma, blood serum, etc.), examples of the component to be analyzed include glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), xcex3-glutamyl transpeptidase (xcex3-GTP), creatine kinase (CPK), triglyceride (TG), amylase (Amy), HDL-cholesterol (HDL-C), and alkaline phosphatase (ALP).